1. Field of the Invention
This invention is directed toward an improved door assembly.
The invention is more particularly directed toward an improved plug door assembly.
2. Description of the Prior Art
Plug doors, generally employed on railway cars, are well known. The plug door is mounted on horizontal rails for longitudinal sliding movement between an open position, where it is located alongside an opening in the wall of a railway car and adjacent the wall, and an intermediate position where it overlies the opening. Means are provided for moving the door laterally between the intermediate position and a closed position where it lies within the opening, generally flush with the wall. In the closed position, the door is "plugged" into the opening.
A pair of vertical crankshafts usually mount the door to the rails. The crankshafts are rotatably mounted on the outer face of the door and extend past the upper and lower ends of the door to be fastened to guide means longitudinally movable but laterally immovable on the rails. Each crankshaft has a horizontal crank arm on the upper and lower portion of its length between the door and the rails. Rotation of the crankshafts will laterally move the attached door, via the crank arms, between the intermediate and closed positions.
Separate means are usually provided for locking the door in the closed position. Canadian Pat. No. 393,756, issued Jan. 7, 1941, Dwyer, by way of example, shows such a typical arrangement. The resulting structure is quite complicated, however, requiring as it does separate mechanisms to both move the door laterally of the rails, and to lock it. In addition, with good door seals, it is often very difficult to open the tight-fitting door.
It is known that the door moving mechanism and the locking mechanism can be combined in an attempt to simplify the structure. Such a structure is shown in Canadian Pat. No. 815,299, issued June 17, 1969, Soddy et al. This patented structure, however, requires modification of the door frame to accommodate the locking means and thus does not really simplify the structure, and the difficulty encountered in opening tight-fitting doors remains.